Process for desulfurizing petroleum distillates using a spent platinum reforming catalyst



2,916,443 OLEUM DISTILLATES NT PLATINUM REFORIIING Filed Aug. 8, 1955 M- D. RIORDAN ETAL SULFURIZING PETR Dn s, 1959 PROCESS FOR DE United States Patent PROCESS FOR DESULFURIZING PETROLEUM DIS--l TILLATES USING Ay SPENT PLATINUM' REFORM- ING CATA-LYST Michael D. Riordan, Fishkill, and Herbert E. Vermillion, Wappingers- Falls, N.Y., assignors tol Texaco' Inc., a corporation of Delaware Application August 8, 1955, SeriaINo. 526,813

5 Claims. (Cl. 208-217)V This invention relates to a hydrocarbon conversion process. More particularly, it relates to a process for desulfurizing middle distillates by hydrodesulfurization employing a supported platinum catalyst.

Middle distillate isa term applied to petroleum fractions higher boiling than gasoline and lower boiling than lubricating oil fractions. Kerosene, diesel fuel, distillate fuel oil, and gas oil, for example, are included' by the term middle distillate. Crude petroleum oils and the middle distillates produced therefrom contain varying types and amounts of sulfur compounds. These sulfur compounds may be objectionable because of bad odor and the harmful effects on stability, corrosiveness and burning characteristics of the products in which they are found. Numerous means have been used to remove sulfur compounds or to convert them to less objectionable forms. These means have included clay treating, acid treating, copper sweetening',A doctor sweetening, solvent extraction and mild hydrogenation. The mild dehydrogenation processes heretofore used are commonly carried out by passing the oil to be treated in admixture with hydrogen over a sulfur resistant hydrogenation catalyst at temperatures of 700 F. to 800 F. and at pressures of 500 to 1000 p.s.i. Catalysts commonly used for mild hydrogenation of middle distillates include tungsten-sulfide, nickel-sulfide, cobalt molybdate and chromia alumina.

It has now been found that middle distillate oils mayl be desulfurized by mild hydrogenation eiciently and with high selectivity when employing a supported platinum catalyst. By the process of this invention, middle distillates are desulfurized by mild hydrogenation in the presence of av supported platinum catalyst; Substantial desulfurization may be obtained at temperatures as low as 500 F. Higher temperatures up to about 800 F. may be employed althoughV at this temperature and higher, undesired reactions, such as hydrocracking or dehydrogenation, may become. pronounced. These reactions are undesirable inmiddle distillate processing since they tend to alter theboilingrange and increase. thearomaticity of the product. These effects in turn may degrade the burning characteristics of kerosene or fuel oil and lower the diesel index or..cetane number of diesel fuels. Preferred temperatures for. the process of this invention' are inthe range of.. S50 to 700 .F. The process of this invention may be. performedv at pressures of about 200 to about 1000 pounds per square inch. Increasing the pressure tends to suppress dehydrogenation of naphthenes to aromatics. Preferred pressures are in the range of about 400 to about 1000 p.s.i. Space velocities of about 0.1 to 10.0 volumes of oil per hour per volume of catalyst may be employed but space velocities of about 0.5 to 3.0 are preferred.

The catalyst employed in the process of this invention is platinum on alumina. It is desirable that the catalyst be substantially free from acidic constituents which tend to promote cracking. The platinum-alumina catalyst contains a small proportion of platinum, for example, l to 2% by Weight, or less. Usuallythe" amount isless than 1%. A catalyst composed of 0.57% platinum on gammav alumina has provedentirely satisfactory. The' surface area of the catalystr does' notv appear particularly' critical and catalystv with both high surface' areas and low surface areas may be satisfactorily used.

In a specific example of the invention, a platinumalumina catalyst is prepared to contain 0.5% platinum by weight on alumina.. Al solution of 25 Igrams of H2PtCl6.6H2O in 1200 ccs. offvvater are saturated withY hydrogen sulfide by bubbling the gas throughr the solution for one-half hour to form a PtS2. The PtS2 slurry is mixed with 1990 grams of' freshly calcined 81 tol 14 mesh alumina having a typical analysis asfollows:

` Percent A1203 961.00 F'e203 t 0.05 S102 Nago 0.10 T102 0.02 H2O 3 .73

and a specific surface of 59.5 m.2/g. after calcining. 240cc. of 30% hydrogen peroxide is added to the alumina-platinum sulfide mixture and allowed to stand for one hour, after which the mixture is dried on a' steam'- plate. Y

Another catalyst which is suitableV for the' process of this invention, comprises platinum, alumina, and a' coinbined halogen. Such a catalyst may have a compositionl Another advantage of this process is that middle distillates may be selectively desulfurized by mildl hydrogenation without substantial hydrocracking or reforming of naphthenes to aromatics.

The accompanying drawing diagrammatically illustrates the process of this invention. Although the drawing illustrates one arrangement of apparatus in whichthe process of this invention may be practiced, it is not intended to limit the invention to the particular apparatus or material described.

A middle distillate feed stock from external storage,

not shown, is admitted to the system through line 1 and' charged by pump 2 through line 3. Hydrogen or ahydrogen-containing gas in line 5 is combined with the middle distillate in line 3 and the combined stream-passes to heater 4 where it is heated to reaction temperature. Heater effluent passes through-transfer line 6 and into reactor 7 which contains a supported platinum catalyst. In reactor 7, a portion of the hydrogen reacts with'sul-l fur present in the middle distillateV feed to form hyd'rogen sulfide. The reactor effluent flows through li'ne 8, cooler 9 and isdischarged into gas separator 10. Mid-- dle distillate product of reduced sulfur content is withdrawn through line 11 and is discharged through valve 12 to external storage, not shown. The gas separated in gas separator 10 comprises unreacted hydrogen and hydrogen sulfide. This gas is withdrawn from gas separator 10 through line 13 and may be recycled by compressor 14 through valve 15 and line 5. Hydrogen sulfide produced by the desulfurization reaction may be withdrawn from the system by bleeding gas through valve 16 and line 17. Hydrogen sulfide may also be removed from the recycle gas by diverting at least a por- Patented Dec. 8, 1'959 A kerosene containing 0.49 weight percent sulfur and having an aniline point of 136.4 F. from a high sulfur crude oil is desulfurized by mild hydrogenaton using a catalyst having the composition (by weight) 0.3% Pt, 0.6% AlF3J/2H2O, 99.1% A1203 at a pressure of 250 p.s.i.g. and with a hydrogen flow rate of 2,727 cubic feet per barrel. The results which are obtained at various temperatures and space velocities are given in the following tabulation:

Y Volumetrie Sulfur, Wt. Aniline Temp., F. Space Percent Point, F. Velocity It will be noted that over 98% of the sulfur is removed frorn the kerosene by mild hydrogenation with a supported platinum catalyst at a temperature of 602 F. and at a space velocity of 0.5. It will also be noted that at 804 F. with a space velocity of 2, more than 96% of the sulfur is removed. However, the lowering of the aniline point indicates that at this temperature (804 F.) reforming of naphthenes to produce aromatics may occur.

Example II A kerosene containing 0.49 weight percent sulfur and having an aniline point of 136.4 F. from a high sulfur crude oil is desulfurized by mild hydrogenation using a catalyst having the composition 0.5% platinum on alumina at a pressure of 400 p.s.i.g. and with a hydrogen ow rate of 14,387 cubic feet per barrel. The results which are obtained at various temperatures and space velocities are given in the following tabulation:

volumetric Sulfur, Wt. Anline Temp., F. Space Percent Point, D F. Velocity It will be noted that at 501 F. with a space velocity of 1.0, over 73% of the sulfur is removed. At tem- .4 peratures of about 605 F. and 0.5 space velocity, over 99% of the sulfur is removed. The treatment shown by this example results in an increase in the aniline point of the product at all temperatures below about 750 F. which indicates that substantial dehydrogenation of naphthenes to form aromatics does not occur.

Although this invention has been described in connection with xed bed catalytic reactors, it is to be understood that the reaction may be carried out in a reactor containing a dense phase fluidized bed of catalyst, or in an entrained catalyst reaction system.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A process for desulfurizing a middle distillate which comprises contacting a sulfur containing middle distillate with hydrogen at a temperature between about 500 F. and 800 F., a pressure between about 200 and 1000 p.s.i. and a space velocity between about 0.1 and l0 volumes of distillate per hour per volume of catalyst in the presence of a platinum on alumina catalyst, said catalyst having been conditioned by the catalytic reforming of gasoline stock and having become spent for reforming purposes, said desulfurization being characterized by the substantial absence of cracking or dehydrogenation.

2. The process of claim 1 in which the middle distillate is kerosene.

3. The process of claim 1 in which the middle distillate is a gas oil.

4. The process of claim 1 in which the middle distillate is diesel fuel.

5. A process for desulfurizing a middle distillate which comprises contacting a sulfur containing middle distillate with hydrogen at a temperature between about 500 F. and 750 F., a pressure between about 250 and 400 p.s.. and a space velocity between about 0.5 and 1.0 volume of distillate per hour per volume of catalyst in the presence of a platinum on alumina catalyst, said catalyst having been conditioned by the catalytic reforming of gasoline stock and having become spent for reforming purposes, said desulfurization process being characterized by the substantial absence of cracking and dehydrogenation.

References Cited in the file of this patent UNITED STATES PATENTS 2,116,061 Dorrer May 3, 1938 2,401,334 Burk et al. June 4, 1946 2,437,532 Huifman Mar. 9, 1948 2,440,673 Jones May 4, 1948 2,542,471 Brandon June 15, 1949 2,542,970 Jones Feb. 27, 1951 2,547,380 Fleck Apr. 3, 1951 2,608,534 Fleck Aug. 26, 1951 2,651,598 Ciapetta Sept. 8, 1953 2,658,028 Haensel Nov. 3, 1953 2,722,501 Kassel Nov. 1, 1955 2,724,683 Nadro Nov. 22, 1955 2,773,007 Gerhold Dec. 4, 1956 2,833,698 Patton et al. May 6, 1958 

1. A PROCESS FOR DESULFURIZING A MIDDLE DISTILLATE WHICH COMPRISES CONTACTING A SULFUR CONTAINING MIDDLE DISTILLATE WITH HYDROGEN AT A TEMPERATURE BETWEEN ABOUT 500*F. AND 800*F., A PRESSURE BETWEEN ABOUT 200 AND 1000 P.S.I. AND A SPACE VELOCITY BETWEEN ABOUT 0.1 TO 10 VOLUMES OF DISTILLATE PER HOUR PER VOLUME OF CATALYST IN THE PRESENCE OF A PLATINUM ON ALUMINA CATALYST, SAID CATALYST HAVING BEEN CONDITIONED BY THE CATALYTIC REFORMING OF GASOLINE STOCK AND HAVING BECOME SPENT FOR REFORMING PURPOSES, SAID DESULFURIZATION BEING CHARACTERIZED BY THE SUBSTANTIAL ABSENCE OF CRACKING OR DEHYDROGENATION. 